ASTM_F_2771_-_10.pdf

Designation:F277110Standard Test Method forDetermining the Luminance Curve of an ElectroluminescentLamp at Ambient Conditions1This standard is issued under the fixed designation F2771;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method establishes the procedures for deter-mining the visible performance change,which is defined byluminance,color and cosmetic appearance of an electrolumi-nescent lamp during operation over an extended time.1.2 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2F1595 Practice for Viewing Conditions for Visual Inspectionof Membrane SwitchesF2359 Test Method for Determining Color of a MembraneSwitch Backlit with Diffuse Light SourceF2360 Test Method for Determining Luminance of a Mem-brane Switch Backlit with Diffuse Light Source3.Terminology3.1 Definitions:3.1.1 luminance,nmeasure of the brightness or luminousintensity of light,usually expressed in units of candelas persquare metre(cd/m2)or foot lamberts.1 fL=3.426 cd/m2.3.1.2 luminance curve,na graphical representation of thevariation of luminance with time(implicitly under unvaryingoperating conditions).3.1.3 electroluminescent lamp(EL lamp),nessentially acapacitor structure with phosphor and a dielectric sandwichedbetween electrodes,one of which is transparent to allow lightto escape.Application of an ac voltage across the electrodesgenerates a charging field within the phosphor,which causes itto emit light.3.1.4 time to half luminance(THL),nthe elapsed operat-ing time over which the luminance of a lamp maintained underconstant power conditions is reduced to 50%of its initialvalue.3.1.5 membrane switch,na momentary switching device,in which at least one contact is on,or made of,a flexiblesubstrate.4.Summary of Test Method4.1 This test method includes an initial measurement of theluminance,color,and appearance of a lamp when poweredwith a specified voltage source.After initial characterization,the lamp is maintained under the same power conditions for anextended interval in a controlled environment designed tointerfere minimally with the operating characteristics of thelamp.The luminance,color and appearance of the lamps undertest are measured and recorded at a predetermined schedulethroughout the test(initially the intervals are shorter to capturethe rapid rate of change and longer as the test progresses).Oneoutput of the measurement is to identify the time of operationby which the measured luminance is reduced to half thatrecorded at the initial characterization.5.Significance and Use5.1 To provide a standardized test method that can be usedfor a valid comparison of luminance time curves,color changesand cosmetic changes between lamps of various designs,fabrication techniques,and sources.6.Interferences6.1 HumidityPerformance characteristics can be skewedwith the change of humidity.6.2 TemperaturePerformance characteristics can beskewed with the change of temperature.6.3 PowerPerformance characteristics can be skewedwith variations in the voltage,frequency and waveform of thepower applied to the lamp.1This test method is under the jurisdiction of ASTM Committee F01 onElectronics and is the direct responsibility of Subcommittee F01.18 on MembraneSwitches.Current edition approved May 1,2010.Published June 2010.Originallyapproved in 2009.Last edition approved in 2009 as F2771-09.DOI:10.1520/F2771-10.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 7.Apparatus7.1 Power source capable of providing an appropriate acvoltage,frequency and waveform.For example,operation at110 6 3 VRMS,at 400 6 10 Hz,square wave which isprevalent in the industry.7.2 Luminance measurement equipment as specified in TestMethod F2360.7.3 Color measurement equipment as specified in TestMethod F2359.8.Hazards8.1 8.1 The procedure requires the verification of highvoltage ac power.Proper precautions against personal hazardsshould be followed.9.Preparation of Apparatus9.1 A location should be established in which the lamp canremain while powered for the duration of the test,free frominterference and in an environment of subdued ambient light.The location should minimize interference from radianceproduced by other samples under test.10.Condition